DE1571417B1 - PROCESS FOR THE PRODUCTION OF ZIRCONIUM SILICATE COLORED BODIES - Google Patents

Description

Ceramic pigments based on zirconium silicate with built-in coloring elements are used for coloring glazes, engobes (coatings made of ceramic.! material with fluxes) and masses (made of ceramic material and plastics) as well as for the production of underglaze colors very appreciated.

This Zirkonfarbkörper have in lead-free, zirconium-containing glazes stability up to 1250 ⁰ C.

They are created by calcining a mixture that consists of the following components:

1. Zirconium oxide or zirconium oxide-forming compounds such as zirconium oxychloride, zirconium sulfates, zirconium oxide hydrates. · - · ^χ ■

2. Silicic acid (SiO ₂ ) :, '.':.;

3. Color-giving compounds of the transition metals, which e.g. contain the elements vanadium, praseodymium, Iron, chrome, nickel, and. Contains cobalt. \

4. Alkali halide, mainly fluorides and chlorides of sodium, as a mineralizer (more reactive Additive).

In order to obtain the corresponding zirconium compounds, in particular zirconium oxide, it is customary in most cases to convert the naturally occurring zirconium sand (zirconium silicate, ZrSiO ₄ ) by melting or annealing with soda or caustic soda or by reacting sodium oxide with zirconium silicate to form sodium zirconium silicate To convert (Na ₂ ZrSiO ₅ ), to separate silicic acid and the alkali component from this compound by the action of acid and to produce zirconium oxide from the thus separated ZiFcon compound, preferably basic zirconium sulfate, by kajzinizing, which is required for the "above" described pigments.

It is also known by the action of acids on sodium zirconium silicate by appropriately guided Treatment to remove only the alkali, including the relatively difficult to process zirconium oxide-silica mixtures need to be washed out. The products obtained in this way are treated with the addition of coloring metal compounds and mineralizers converted into the desired zirconium silicate pigments by renewed annealing.

A zirconium dioxide-silica precursor is known to use for the production of color bodies, the dry conversion of sodium zirconium silicate obtained with ammonium salts and subsequent washing out of the corresponding sodium salt will. ■

All of these processes have the disadvantage that for the production of the zirconium component Products multi-stage processes are necessary, especially the production must take place on the wet route. Since the products are relatively difficult to process, these wet processes require a relatively high expenditure on equipment and working time.

It has now been found that such color bodies can be produced in a particularly simple manner in a one-step process by heating a mixture of sodium zirconium silicate with an ammonium salt with the addition of a coloring metal compound to temperatures of 750 to 130O ⁰ C, the used Ammonium compound is added in amounts that at least correspond to the stoichiometric alkali content of the sodium zirconium silicate. In this process, no wet processes are required until the color body is formed, rather a direct conversion of the sodium zirconium silicate that can be obtained by dry means takes place in the desired color body .

So it is possible, that in the extraction of Zirconium dioxide "precursor sodium zirconium silicate" without further conversion directly for production of color bodies to be used.

It is surprising that this direct reaction is possible with sodium zirconium silicate, since it is known was that such a reaction is not possible with zirconium silicate. As ammonium salts can Ammonium sulfate chloride or fluoride can be used, whereby it is not necessary to convert the Add a mineralizer to the mixture. After the implementation it is only necessary to use the resulting To wash out alkali compounds from the color bodies to be obtained.

In this reaction, color bodies are obtained, some of which are characterized by a special color intensity.

' to draw. . ' .

If necessary, an alkaline earth metal halide or a lead compound can also be added as a mineralizer be a measure, which in some cases can be used to lower the reaction temperature or has a beneficial effect on influencing the color intensity.

Sodium zirconium silicate (23.3 ° / ₀ Na ₂ O)
(by hydrothermal digestion of
ZrSiO _{4 obtained} with NaOH)

Sodium zirconium silicate (25 ° / ₀ Na ₃ O)
(by sintering 1.3 mol of Na ₂ CO ₃ with
1 mole of ZrSiO ₄ obtained)

Ammonium hydrogen sulfate

Ammonium sulfate

Ammonium chloride

Ammonium metavanadate

Iron oxide

Praseodymium oxide

Nickel oxide

Bismuth oxide

Lead oxide

Annealing temperature, ⁰ C

Appearance in glaze

- - - - 100.0 - 100.0 100.0 100.0 100.0 100.0 67.5 - - - - - 63.93 76.00 76.00 42.75 63.93 - - - - : 3.86 - 3.61 3.93 3.93 3.93 ■ - ■■ _- - c: ~. ' 2.73 2.68 - - 2.05 - - - - 7.5 - - - __ 7.5 850 1050 1050 1250 1050 1050 very powerful green bluesti- powerful very blue blue chiges yellow powerful green yellow

100.0
63.93

1150
pink brown

example

For the preparation of zirconium-vanadium blue Natriumzirkonsilikat 245 g are mixed with 132 g of ammonium sulfate and 8 g of vanadium pentoxide and annealed at 1050 ⁰ C 5. The product obtained in this way is ground with water in a ball mill, washed free of sulfate and dried.

The result was a color body which was in relation to the corresponding ones produced by other processes Zircon Vanadium Blue stains had a more intense hue.

Further examples of color bodies produced according to the invention are given in the table.

Claims (5)

Patent claims: 1. A process for the production of zirconium silicate color bodies, characterized in that a mixture of sodium zirconium silicate with an ammonium salt with ao addition of a coloring metal compound is ^{heated to temperatures of 750 to 1300 0} C, the ammonium compound used is added in amounts that are at least the alkali component of sodium zirconium silicate correspond stoichiometrically. 2. The method according to claim 1, characterized in that sodium zirconium silicate is used produced by melting or annealing zirconium silicate with soda or caustic soda will. 3. The method according to claim 1, characterized in that ammonium salts as mixtures can be used. 4. The method according to claim 1, characterized in that small amounts of a mineralizer or mineralizer mixtures are added. 5. The method according to claim 1, characterized in that a sodium zirconium silicate is used is made by hydrothermal decomposition of zirconium silicate with alkali under pressure is generated.